I have posted this, in various forms, here before. I'm sure I could post it ad nauseum and many here would disregard it because they don't understand it, or find some weird fault with it. This is about rational argument. The observations, facts and conclusions below cannot easily be refuted.
This chart says it all:
Figure 1: Change in spectrum from 1970 to 1996 due to trace gases. 'Brightness temperature' indicates equivalent blackbody temperature (Harries 2001).
[Butcherboy note: I'm not sure why Skeptical Science says 1996 but the peer reviewed paper abstract below says 1997... perhaps its a worldwide conspiracy... oooohhhhh.... sssshhhhh, please don't tell anyone...]
Nature 410, 355-357 (15 March 2001) | doi:10.1038/35066553; Received 17 May 2000; Accepted 15 January 2001
Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997
John E. Harries, Helen E. Brindley, Pretty J. Sagoo & Richard J. Bantges
Space and Atmospheric Physics Group, Blackett Laboratory, Imperial College, London SW7 2BW, UK
Correspondence to: John E. Harries Correspondence and requests for materials should be addressed to J.E.H. (e-mail: Email: [email protected]).
The evolution of the Earth's climate has been extensively studied1, 2, and a strong link between increases in surface temperatures and greenhouse gases has been established3, 4. But this relationship is complicated by several feedback processes—most importantly the hydrological cycle—that are not well understood5, 6, 7. Changes in the Earth's greenhouse effect can be detected from variations in the spectrum of outgoing longwave radiation8, 9, 10, which is a measure of how the Earth cools to space and carries the imprint of the gases that are responsible for the greenhouse effect11, 12, 13. Here we analyse the difference between the spectra of the outgoing longwave radiation of the Earth as measured by orbiting spacecraft in 1970 and 1997. We find differences in the spectra that point to long-term changes in atmospheric CH4, CO2 and O3 as well as CFC-11 and CFC-12. Our results provide direct experimental evidence for a significant increase in the Earth's greenhouse effect that is consistent with concerns over radiative forcing of climate."
Here is a simpler explanation from Skeptical Science:
"Satellite measurements of outgoing longwave radiation
In 1970, NASA launched the IRIS satellite that measured infrared spectra between 400 cm-1 to 1600 cm-1. In 1996, the Japanese Space Agency launched the IMG satellite which recorded similar observations. Both sets of data were compared to discern any changes in outgoing radiation over the 26 year period (Harries 2001). The resultant change in outgoing radiation was as follows:
[see chart above]
What they found was a drop in outgoing radiation at the wavelength bands that greenhouse gases such as carbon dioxide (CO2) and methane (CH4) absorb energy. The change in outgoing radiation is consistent with theoretical expectations. Thus the paper found "direct experimental evidence for a significant increase in the Earth's greenhouse effect".
This result has been confirmed by subsequent papers using more recent satellite data. The 1970 and 1997 spectra were compared with additional satellite data from the NASA AIRS satellite launched in 2003 (Griggs 2004). This analysis was extended to 2006 using data from the AURA satellite launched in 2004 (Chen 2007). Both papers found the observed differences in CO2 bands matching the expected changes from rising carbon dioxide levels. Thus we have empirical evidence that increased CO2 is causing an enhanced greenhouse effect."
Basically, more CO2 and CH4 (and other minor greenhouse gases) caused less infrared radiation to escape the earth's atmosphere in 1997 compared to 1970 i.e. the radiative heat balance is changing causing the earth to warm up. Very elegant, very simple.
